Inducible nitric oxide synthase, but not xanthine oxidase, is highly expressed in interstitial pneumonias and granulomatous diseases of human lung

Vistusertib improves pulmonary inflammation and fibrosis by modulating inflammatory/oxidative stress mediators via suppressing the mTOR signalling

INTRODUCTION

Inflammation and oxidative stress are key factors in the development of pulmonary fibrosis (PF) by promoting the differentiation of fibroblasts through modulating various pathways including Wnt/β-catenin, TGF-β and mTOR signalling.

OBJECTIVE AND METHODS

This study aimed to evaluate the effects and elucidate the mechanisms of vistusertib (VSB) in treating pulmonary inflammation/fibrosis, specifically by targeting the mTOR pathway using various in vitro and in vivo models.

RESULTS

Lipopolysaccharide (LPS)-induced inflammation model in macrophages (RAW 264.7), epithelial (BEAS-2B) and endothelial (HMVEC-L) cells revealed that treatment with VSB significantly reduced the IL-6, TNF-α, CCL2, and CCL7 expression. TGF-β induced differentiation was also significantly reduced upon VSB treatment in fibrotic cells (LL29 and DHLF). Further, bleomycin-induced inflammation and fibrosis models demonstrated that treatment with VSB significantly ameliorated the severe inflammation, and lung architectural distortion, by reducing the inflammatory markers expression/levels, inflammatory cells and oxidative stress indicators. Further, fibrosis model results exhibited that, VSB treatment significantly reduced the α-SMA, collagen and TGF-β expressions, improved the lung architecture and restored lung functions.

CONCLUSION

Overall, this study uncovers the anti-inflammatory/anti-fibrotic effects of VSB by modulating the mTOR activation. Although VSB was tested for lung fibrosis, it can be tested for other fibrotic disorders to improve the patient's survival and quality of life.

Purification and activity evaluation of novel anti-inflammatory peptides from pearl oyster (Pinctada martensii) hydrolysates

Pearl oyster meat, a by-product of pearl production, is rich in protein, but has a low utilization rate. Our previous study showed that pearl oyster meat hydrolysates have potential anti-inflammatory activity. In this study, highly active peptides from pearl oyster meat hydrolysates were purified, identified, and extracted, and their anti-inflammatory activity was further investigated. A total of 206 peptides were identified, and three novel anti-inflammatory peptides, TWP (402.1903 Da), TAMY (484.1992 Da) and FPGA (390.1903 Da), were screened by molecular docking. The molecular docking results showed that TWP, TAMY and FPGA can bind to key regions in the cyclooxygenase-2 (COX-2) active site. Furthermore, the three anti-inflammatory peptides can effectively regulate the release of inflammatory mediators from RAW264.7 macrophages by reducing the levels of nitric oxide (NO) and pro-inflammatory cytokines (such as TNF-α, IL-6 and IL-1β), and increasing the production of anti-inflammatory cytokine IL-10, showing great anti-inflammatory activity. This study provides a new theoretical reference for the development of functional foods or nutritional supplements with natural anti-inflammatory effects.

Gasotransmitters: Potential Therapeutic Molecules of Fibrotic Diseases

Fibrosis is defined as the pathological progress of excessive extracellular matrix (ECM), such as collagen, fibronectin, and elastin deposition, as the regenerative capacity of cells cannot satisfy the dynamic repair of chronic damage. The well-known features of tissue fibrosis are characterized as the presence of excessive activated and proliferated fibroblasts and the differentiation of fibroblasts into myofibroblasts, and epithelial cells undergo the epithelial-mesenchymal transition (EMT) to expand the number of fibroblasts and myofibroblasts thereby driving fibrogenesis. In terms of mechanism, during the process of fibrosis, the activations of the TGF-β signaling pathway, oxidative stress, cellular senescence, and inflammatory response play crucial roles in the activation and proliferation of fibroblasts to generate ECM. The deaths due to severe fibrosis account for almost half of the total deaths from various diseases, and few treatment strategies are available for the prevention of fibrosis as yet. Recently, numerous studies demonstrated that three well-defined bioactive gasotransmitters, including nitric oxide (NO), carbon monoxide (CO), and hydrogen sulfide (H₂S), generally exhibited anti-inflammatory, antioxidative, antiapoptotic, and antiproliferative properties. Besides these effects, a number of studies have reported that low-dose exogenous and endogenous gasotransmitters can delay and interfere with the occurrence and development of fibrotic diseases, including myocardial fibrosis, idiopathic pulmonary fibrosis, liver fibrosis, renal fibrosis, diabetic diaphragm fibrosis, and peritoneal fibrosis. Furthermore, in animal and clinical experiments, the inhalation of low-dose exogenous gas and intraperitoneal injection of gaseous donors, such as SNAP, CINOD, CORM, SAC, and NaHS, showed a significant therapeutic effect on the inhibition of fibrosis through modulating the TGF-β signaling pathway, attenuating oxidative stress and inflammatory response, and delaying the cellular senescence, while promoting the process of autophagy. In this review, we first demonstrate and summarize the therapeutic effects of gasotransmitters on diverse fibrotic diseases and highlight their molecular mechanisms in the process and development of fibrosis.

Adelmidrol: A New Promising Antioxidant and Anti-Inflammatory Therapeutic Tool in Pulmonary Fibrosis

BACKGROUND

Chronic pulmonary diseases are characterized by airway remodeling due to complex multicellular responses and the production of free oxygen radicals. They lead to a progressive decline of pulmonary functions. Adelmidrol is an analogue of palmitoylethanolamide (PEA), which is a well-known anti-inflammatory and anti-oxidant compound. In this study, we investigated the efficacy of adelmidrol (10 mg/Kg) for bleomycin-induced pulmonary fibrosis in mice.

METHODS

Bleomycin intratracheal administration was performed on the first day and for the following twenty-one days, mice were treated with adelmidrol (10 mg/Kg).

RESULTS

The survival rate and body weight gain were recorded daily. At the end of the experiment, adelmidrol-administered animals showed reduced airway infiltration by inflammatory cells, Myeloperoxidase (MPO) activity, and pro-inflammatory cytokine overexpression (IL,6 IL-1β, TNF-α, and TGF-1β). Moreover, adelmidrol treatment was able to manage the significant incapacity of antioxidants and elevation of the oxidant burden, as shown by the MDA, SOD, and GSH levels and decreased nitric oxide production. It was also able to significantly modulate the JAK2/STAT3 and IκBα/NF-kB pathway. Histologic examination of the lung tissues showed reduced sample injury, mast cell degranulation, chymase activity, and collagen deposition.

CONCLUSIONS

In sum, our results propose adelmidrol as a therapeutic approach in the treatment of pulmonary fibrosis.

Zingerone ameliorates oxidative stress and inflammation in bleomycin-induced pulmonary fibrosis: modulation of the expression of TGF-β1 and iNOS

Idiopathic pulmonary fibrosis (IPF) is an interstitial lung disease with limited treatment options. Zingerone found in ginger (Zingiber officinale L.) has many pharmacological effects, especially antiinflammatory and antioxidant activity. However, the effect of zingerone on pulmonary fibrosis (PF) is not fully known. The aim of this study was to investigate the effect of zingerone on bleomycin (BLM)-induced PF and its underlying mechanisms. Wistar-albino rats were given single dose of BLM (5 mg/kg, intratracheal) or vehicle (saline). In treatment groups, zingerone (50 and 100 mg/kg, p.o.) was administered orally for 14 days after BLM administration. Rats and lung tissue were weighed to determine lung index. Antioxidant, antiinflammatory effects, and hydroxyproline content of zingerone were determined by ELISA method. Pulmonary inflammation, collagen deposition, and fibrosis score were determined with Hematoxylin-Eosin (HxE) and Masson's trichrome staining. Transforming growth factor-beta 1 (TGF-β1) and inducible nitric oxide synthase (iNOS) expressions were detected immunohistochemically. BLM administration increased lipid peroxidation (MDA) and decreased superoxide dismutase (SOD) and glutathione peroxidase (GPx) activity. In addition, BLM caused increased levels of tumor necrosis factor alpha (TNF-α) and interleukin-1β (IL-1β) in bronchoalveolar lavage fluid (BALF) and accumulation of collagen bundles. Zingerone administration decreased collagen accumulation, TNF-α and IL-1β levels, MDA level, TGF-β1, and iNOS expression and increased SOD and GPx activity. Histopathological findings supported the results. These results show that zingerone (50 and 100 mg/kg) at both doses significantly contributes to healing of PF by improving inflammation, oxidative stress, and histopathological alterations and by affecting TGF-β1 and iNOS signaling pathways.

The pathophysiological role of mitochondrial oxidative stress in lung diseases

Mitochondria are critically involved in reactive oxygen species (ROS)-dependent lung diseases, such as lung fibrosis, asbestos, chronic airway diseases and lung cancer. Mitochondrial DNA (mtDNA) encodes mitochondrial proteins and is more sensitive to oxidants than nuclear DNA. Damage to mtDNA causes mitochondrial dysfunction, including electron transport chain impairment and mitochondrial membrane potential loss. Furthermore, damaged mtDNA also acts as a damage-associated molecular pattern (DAMP) that drives inflammatory and immune responses. In this review, crosstalk among alveolar epithelial cells, alveolar macrophages and mitochondria is examined. ROS-related transcription factors and downstream cell signaling pathways are also discussed. We conclude that targeting oxidative stress with antioxidant agents, such as thiol molecules, polyphenols and superoxide dismutase (SOD), and promoting mitochondrial biogenesis should be considered as novel strategies for treating lung diseases that currently have no effective treatment options.

Ultramicronized palmitoylethanolamide (PEA-um(®)) in the treatment of idiopathic pulmonary fibrosis

Pulmonary fibrosis is a chronic condition characterized by progressive scarring of lung parenchyma. The aim of this study was to examine the effects of an ultramicronized preparation of palmitoylethanolamide (PEA-um(®)), an endogenous fatty acid amide, in mice subjected to idiopathic pulmonary fibrosis. Idiopathic pulmonary fibrosis was induced in male mice by a single intratracheal administration of saline with bleomycin sulphate (1mg/kg body weight) in a volume of 100μL. PEA-um(®) was injected intraperitoneally at 1, 3 or 10mg/kg 1h after bleomycin instillation and daily thereafter. Animals were sacrificed after 7 and 21days by pentobarbitone overdose. One cohort of mice was sacrificed after seven days of bleomycin administration, followed by bronchoalveloar lavage and determination of myeloperoxidase activity, lung edema and histopathology features. In the 21-day cohort, mortality was assessed daily, and surviving mice were sacrificed followed by the above analyses together with immunohistochemical localization of CD8, tumor necrosis factor-α, CD4, interleukin-1β, transforming growth factor-β, inducible nitric oxide synthase and basic fibroblast growth factor. Compared to bleomycin-treated mice, animals that received also PEA-um(®) (3 or 10mg/kg) had significantly decreased weight loss, mortality, inflammation, lung damage at the histological level, and lung fibrosis at 7 and 21days. PEA-um(®) (1mg/kg) did not significantly inhibit the inflammation response and lung fibrosis. This study demonstrates that PEA-um(®) (3 and 10mg/kg) reduces the extent of lung inflammation in a mouse model of idiopathic pulmonary fibrosis.

Increased exhaled nitric oxide precedes lung fibrosis in two murine models of systemic sclerosis

Exhaled nitric oxide (NO) is increased as a result of lung inflammation, which in turn causes subsequent interstitial lung disease in patients with systemic sclerosis (SSc). However, the exact time course of inflammatory and fibrotic changes in the SSc lung has not yet been described. Our objective was to assess the chronological evolution of lung inflammatory and fibrotic processes in mice pre-treated with hypochlorous acid (HOCl) or bleomycin. C57BL/6 mice were randomized into three groups receiving subcutaneous injections of HOCl, bleomycin, or PBS for 2, 4 or 6 weeks. Exhaled NO (eNO) was measured at the end of each injection period and after 2 resting weeks without injection (8 week group). Mice were then sacrificed to obtain skin and lung tissues to measure fibrotic changes and NO synthases (NOS) expression. Increased eNO, inducible NOS and nitrotyrosine expression in bronchial epithelium, lung neutrophils and macrophages were observed at early phases in both HOCl- and bleomycin-treated mice. Conversely, lung vascular endothelial NOS expression decreased significantly at 6th and 8th weeks. Skin fibrosis was significantly increased from the 4th week and lung fibrosis from 6th week. We conclude that lung inflammation occurs early after injury as reflected by increased exhaled NO and inducible NOS expression, and precedes fibrotic changes in skin and lungs of mice pre-treated with bleomycin and HOCl. Early detection and treatment of pulmonary inflammation might be useful in preventing subsequent occurrence of lung fibrosis in SSc patients.

Nitric oxide exerts protective effects against bleomycin-induced pulmonary fibrosis in mice

BACKGROUND

Increased expression of nitric oxide synthase (NOS) and an increase in plasma nitrite plus nitrate (NOx) have been reported in patients with pulmonary fibrosis, suggesting that nitric oxide (NO) plays an important role in its development. However, the roles of the entire NO and NOS system in the pathogenesis of pulmonary fibrosis still remain to be fully elucidated. The aim of the present study is to clarify the roles of NO and the NOS system in pulmonary fibrosis by using the mice lacking all three NOS isoforms.

METHODS

Wild-type, single NOS knockout and triple NOS knockout (n/i/eNOS-/-) mice were administered bleomycin (BLM) intraperitoneally at a dose of 8.0 mg/kg/day for 10 consecutive days. Two weeks after the end of the procedure, the fibrotic and inflammatory changes of the lung were evaluated. In addition, we evaluated the effects of long-term treatment with isosorbide dinitrate, a NO donor, on the n/i/eNOS-/- mice with BLM-induced pulmonary fibrosis.

RESULTS

The histopathological findings, collagen content and the total cell number in bronchoalveolar lavage fluid were the most severe/highest in the n/i/eNOS-/- mice. Long-term treatment with the supplemental NO donor in n/i/eNOS-/- mice significantly prevented the progression of the histopathological findings and the increase of the collagen content in the lungs.

CONCLUSIONS

These results provide the first direct evidence that a lack of all three NOS isoforms led to a deterioration of pulmonary fibrosis in a BLM-treated murine model. We speculate that the entire endogenous NO and NOS system plays an important protective role in the pathogenesis of pulmonary fibrosis.

Pulmonary infection, and not systemic inflammation, accounts for increased concentrations of exhaled nitric oxide in patients with septic shock

Nitric oxide (NO) is a key mediator in the pathophysiology of septic shock that can be measured in exhaled breath. To assess whether a pulmonary infection itself or systemic inflammation is responsible for NO production, we determined exhaled NO in ventilated patients with respiratory and non-respiratory septic shock and compared it with the concentration in ventilated intensive care patients without systemic inflammation. In addition, the change of NO production over time and correlations with haemodynamic instability were evaluated. The controls without systemic inflammation, as witnessed by the absence of systemic inflammatory response syndrome criteria and low levels of interleukin-6, had similar concentrations of NO as the patients with non-respiratory septic shock. The respiratory sepsis patients exhaled more NO than the non-respiratory sepsis patients (p = 0.05), and a time dependent decline in time in both groups (p = 0.04). Exhaled NO did not correlate with markers of disease severity, systemic inflammation and haemodynamic instability. These data indicate that the infected lungs are the source of exhaled NO.

New insights into the role of oxidative stress in scleroderma fibrosis

Systemic sclerosis (Scleroderma – SSc) is a connective tissue disorder of unknown aetiology characterized by extensive fibrosis of the skin and visceral organs, by vascular abnormalities and immunological manifestations.

Recent evidence suggest that the cellular redox state may play a significant role in the progression of scleroderma fibrosis. Mechanisms involved include an autoamplification circuit linking ROS, Ras and ERK 1-2 which in turn amplifies and maintains the autocrine loop made up by cytokines, growth factors and their cognate receptors.

This review summarizes the recent progress on the role of oxidative stress in the pathophysiology of scleroderma and disorders characterised by organ fibrosis

NOS2 regulation of LPS-induced airway inflammation via S-nitrosylation of NF-{kappa}B p65

Inducible nitric oxide synthase (NOS2) expression is increased in the airway epithelium in acute inflammatory disorders although the physiological impact remains unclear. We have previously shown that NOS2 inhibits NF-κB (p50-p65) activation in respiratory epithelial cells by inducing S-nitrosylation of the p65 monomer (SNO-p65). In addition, we have demonstrated that mouse lung SNO-p65 levels are acutely depleted in a lipopolysaccharide (LPS) model of lung injury and that augmenting SNO-p65 levels before LPS treatment results in decreased airway epithelial NF-κB activation, airway inflammation, and lung injury. We now show that aerosolized LPS induces NOS2 expression in the respiratory epithelium concomitant with an increase in lung SNO-p65 levels and a decrease in airway NF-κB activity. Genetic deletion of NOS2 results in an absence of SNO-p65 formation, persistent NF-κB activity in the respiratory epithelium, and prolonged airway inflammation. These results indicate that a primary function of LPS-induced NOS2 expression in the respiratory epithelium is to modulate the inflammatory response through deactivation of NF-κB via S-nitrosylation of p65, thereby counteracting the initial stimulus-coupled denitrosylation.

Factors influencing oxidative imbalance in pulmonary fibrosis: an immunohistochemical study

Background. Idiopathic Pulmonary Fibrosis (IPF) is a fatal lung disease of unknown etiology characterized by interstitial fibrosis determining irreversible distortion of pulmonary architecture. Reactive oxygen species (ROS) and markers of oxidative stress play a pivotal role in human IPF pathology, possibly through induction of epithelial-mesenchymal transition (EMT). Methods. We investigated by immunohistochemistry, in UIP and COP tissue samples, the expression of most relevant markers of the molecular interplay involving RAGE, oxidant/antioxidant balance regulation, tissue nitrosylation, and mediators of EMT. Results. In both UIP and COP, the degree of RAGE expression was similarly high, while SODs and i-NOS, diffusely present in COP endoalveolar plugs, were almost absent in UIP fibroblast foci. A lower degree of tissue nitrosilation was observed in UIP than in COP. Conclusions. Fibroblast lesions of UIP and of COP share a similar degree of activation of RAGE, while antioxidant enzyme expression markedly reduced in UIP.

Hemoglobin α and β are ubiquitous in the human lung, decline in idiopathic pulmonary fibrosis but not in COPD

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) and chronic obstructive pulmonary disease (COPD) are disorders of the lung parenchyma. They share the common denominators of a progressive nature and poor prognosis. The goal was to use non-biased proteomics to discover new markers for these diseases.

METHODS

Proteomics of fibrotic vs. control lung tissue suggested decreased levels of several spots in the lung specimens of IPF patients, which were identified as Hemoglobin (Hb) α and β monomers and Hbα complexes. The Hbα and β monomers and complexes were investigated in more detail in normal lung and lung specimens of patients with IPF and COPD by immunohistochemistry, morphometry and mass spectrometry (MS).

RESULTS

Both Hb monomers, in normal lung, were expressed especially in the alveolar epithelium. Levels of Hbα and β monomers and complexes were reduced/lost in IPF but not in the COPD lungs when compared to control lung. MS-analyses revealed Hbα modification at cysteine105 (Cysα105), preventing formation of the Hbα complexes in the IPF lungs. Hbα and Hbβ were expressed as complexes and monomers in the lung tissues, but were secreted into the bronchoalveolar lavage fluid and/or induced sputum supernatants as complexes corresponding to the molecular weight of the Hb tetramer.

CONCLUSIONS

The abundant expression of the oxygen carrier molecule Hb in the normal lung epithelium and its decline in IPF lung are new findings. The loss of Hb complex formation in IPF warrants further studies and may be considered as a disease-specific modification.

Modulation of cytokine and nitric oxide by mesenchymal stem cell transfer in lung injury/fibrosis

Background

No effective treatment for acute lung injury and fibrosis currently exists. Aim of this study was to investigate the time-dependent effect of bone marrow-derived mesenchymal stem cells (BMDMSCs) on bleomycin (BLM)-induced acute lung injury and fibrosis and nitric oxide metabolites and inflammatory cytokine production.

Methods

BMDMSCs were transferred 4 days after BLM inhalation. Wet/dry ratio, bronchoalveolar lavage cell profiles, histologic changes and deposition of collagen were analyzed.

Results

Nitrite, nitrate and cytokines were measured weekly through day 28. At day 7, the wet/dry ratio, neutrophilic inflammation, and amount of collagen were elevated in BLM-treated rats compared to sham rats (p = 0.05-0.002). Levels nitrite, nitrate, IL-1β, IL-6, TNF-α, TGF-β and VEGF were also higher at day 7 (p < 0.05). Degree of lymphocyte and macrophage infiltration increased steadily over time. BMDMSC transfer significantly reduced the BLM-induced increase in wet/dry ratio, degree of neutrophilic infiltration, collagen deposition, and levels of the cytokines, nitrite, and nitrate to those in sham-treated rats (p < 0.05). Fluorescence in situ hybridization localized the engrafted cells to areas of lung injury.

Conclusion

Systemic transfer of BMDMSCs effectively reduced the BLM-induced lung injury and fibrosis through the down-regulation of nitric oxide metabolites, and proinflammatory and angiogenic cytokines.

The selenium analog of the chemopreventive compound S,S'-(1,4-phenylenebis[1,2-ethanediyl])bisisothiourea is a remarkable inducer of apoptosis and inhibitor of cell growth in human non-small cell lung cancer

Lung cancer continues to be the leading cause of cancer deaths throughout the world and conventional therapy remains largely unsuccessful. Although, chemoprevention is a plausible alternative approach to curb the lung cancer epidemic, clinically there are no effective chemopreventive agents. Thus, development of novel compounds that can target cellular and molecular pathways involved in the multistep carcinogenesis process is urgently needed. Previous studies have suggested that substitution of sulfur by selenium in established cancer chemopreventive agents may result in more effective analogs. Thus in the present study we selected the chemopreventive agent S,S'-(1,4-phenylenebis[1,2-ethanediyl])bisisothiourea (PBIT), also known to inhibit inducible nitric oxide synthase (iNOS), synthesized its selenium analog (Se-PBIT) and compared both compounds in preclinical model systems using non-small cell lung cancer (NSCLC) cell lines (NCI-H460 and A549); NSCLC is the most common histologic type of all lung cancer cases. Se-PBIT was found to be superior to PBIT as an inducer of apoptosis and inhibitor of cell growth. Se-PBIT arrested cell cycles at G1 and G2-M stage in both A549 and H460 cell lines. Although both compounds are weakly but equally effective inhibitors of iNOS protein expression and activity, only Se-PBIT significantly enhanced the levels of p53, p38, p27 and p21 protein expression, reduced levels of phospholipase A2 (PLA2) but had no effect on cyclooxygenase-2 (COX-2) protein levels; such molecular targets are involved in cell growth inhibition, induction of apoptosis and cell cycle regulation. The results indicate that Se-PBIT altered molecular targets that are involved in the development of human lung cancer. Although, the mechanisms that can fully account for these effects remain to be determined, the results are encouraging to further evaluate the chemopreventive efficacy of Se-PBIT against the development of NSCLC in a well-defined animal model.

Hypersensitivity pneumonitis

The first few cases of hypersensitivity pneumonitis (HP) were described in the early 20th century in farmers exposed to moldy hay or straw. As then, HP has been ascribed to multiple inhaled antigens found in a large variety of environmental settings. Hypersensitivity pneumonitis results from an exaggerated immune response, which gives rise to acute infection-like symptoms or to progressive, sometimes irreversible lung damage. The diagnosis is based on a combination of clinical characteristics of the disease. Clinical diagnostic criteria have recently been published. The immune mechanisms leading to HP are still incompletely understood. Initially, believed to be a classes III and IV immune response, we now have a clearer understanding of the complex inflammatory events involved. These include the release of pro inflammatory cytokines and a decrease in the immune control mechanisms via surfactant, dendritic and T-regulatory cells. Despite the improved understanding, the treatment and outcome of HP have not changed. Oral corticosteroids remain the only effective drugs and contact withdrawal constitutes the ideal solution. If unchecked, HP can lead to irreversible lung damage in the form of fibrosis or emphysema, respiratory insufficiency and even death.

Peroxiredoxin II expression and its association with oxidative stress and cell proliferation in human idiopathic pulmonary fibrosis

Oxidant burden has been suggested to be a contributor to the pathogenesis of idiopathic pulmonary fibrosis (IPF). The study focused on peroxiredoxin (Prx) II, an antioxidant that has been associated with platelet-derived growth factor (PDGF) signaling and consequent cell proliferation. Localization and expression of Prx II, PDGF receptors (PDGFRalpha, PDGFRbeta), Ki67, and nitrotyrosine were assessed in control (n=10) and IPF/usual interstitial pneumonia (UIP) (n=10) lung biopsies by immunohistochemistry and morphometry. Prx II oxidation was determined by standard and non-reducing Western blots, two-dimensional gel electrophoresis, and mass spectrometry. Prx II localized in the IPF/UIP epithelium and alveolar macrophages. Prx II-positive area in the fibroblastic foci (FF) was smaller than in other parenchymal areas (p=0.03) or in the hyperplastic epithelium (p=0.01). There was no major Prx II oxidation in IPF/UIP compared with the normal lung. The FF showed only minor immunoreactivity to the PDGFRs; Ki67, a marker of cell proliferation; and nitrotyrosine, a marker of oxidative/nitrosative stress. The results suggest that Prx II oxidation does not relate to the pathogenesis of IPF/UIP and that Prx II, PDGFRs, and proliferating cells colocalize in the IPF/UIP lung. Unexpectedly, FF represented areas of low cell proliferation.

Oxidant-antioxidant imbalance as a potential contributor to the progression of human pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common idiopathic interstitial pneumonia. IPF is a disease with poor prognosis and an aggressive nature, and poses major challenges to clinicians. Thus, a large part of research in the area has focused on the pathogenesis on IPF. Characteristic features in IPF include fibrotic lesions devoid of inflammatory cell infiltrates. There are experimental models of lung fibrosis (e.g., bleomycin-induced fibrosis), but they typically contain a prominent inflammatory pattern in the lung, which leads to relatively diffuse lung fibrosis. Nonetheless, experimental models have provided important information about the progression and pathways contributing to the lung fibrosis, including activation of transforming growth factor beta (TGF-beta). Both patient material and experimental models of lung fibrosis have displayed marked elevation of several markers of oxidant burden and signs for disturbed antioxidant/oxidant balance. Several studies also suggest that reactive oxygen species can cause activation of growth-regulatory cytokines, including TGF-beta. In addition, there are indications that endogenous and exogenous antioxidants/redox modulators can influence fibrogenesis, protect the lung against fibrosis, and prevent its progression. Factors that restore the antioxidant capacity and prevent sustained activation of growth-regulatory cytokines may have a therapeutic role in IPF.

Extracellular superoxide dismutase in pulmonary fibrosis

Disruption of the oxidant/antioxidant balance in the lung is thought to be a key step in the development of many airway pathologies. Hence, antioxidant enzymes play key roles in controlling or preventing pulmonary diseases related to oxidative stress. The superoxide dismutases (SOD) are a family of enzymes that play a pivotal role protecting tissues from damage by oxidant stress by scavenging superoxide anion, which prevents the formation of other more potent oxidants such as peroxynitrite and hydroxyl radical. Extracellular SOD (EC-SOD) is found predominantly in the extracellular matrix of tissues and is ideally situated to prevent cell and tissue damage initiated by extracellularly produced ROS. EC-SOD has been shown to be protective in several models of interstitial lung disease, including pulmonary fibrosis. In addition, alterations in EC-SOD expression are also present in human idiopathic pulmonary fibrosis (IPF). This review discusses EC-SOD regulation in response to pulmonary fibrosis in animals and humans and reviews possible mechanisms by which EC-SOD may protect against fibrosis.

Colorectal carcinoma development in inducible nitric oxide synthase-deficient mice with dextran sulfate sodium-induced ulcerative colitis

The overproduction of reactive oxygen and nitrogen species (RONS) may play an important role in ulcerative colitis (UC)-associated carcinogenesis. In order to study the role of nitric oxide (NO) in UC-associated colorectal carcinogenesis, the development of colorectal carcinoma was studied using the DSS-induced and iron-enhanced model of chronic UC in inducible nitric oxide synthase (iNOS)-deficient mice. Female wild-type C57BL/6 (iNOS+/+) and iNOS-/- mice were administered 1% DSS (w/v) through the drinking fluid for 15 DSS cycles and fed twofold iron-enriched diet. Colorectal inflammation and mucosal ulceration of moderate severity were observed in both iNOS+/+ and iNOS-/- mice. Similar tumor incidence and multiplicity in the colon were observed that 15 out of 23 (65.2%) iNOS+/+ mice developed colorectal tumors with a tumor multiplicity of 1.47+/-0.17 (mean+/-SE) after 15 DSS cycles, and 13 out of 19 (68.4%) iNOS-/- mice developed colorectal tumors with a tumor multiplicity of 2.08+/-0.21. Histopathologically, the tumors were confirmed to be well-differentiated adenocarcinomas. Nitrotyrosine, an indicator of peroxynitrite-caused protein modification, was detectable by immunohistochemistry in inflammatory cells and epithelial cells of the colon in iNOS+/+ and iNOS-/- mice, and no difference in staining intensity was observed between the two groups. Immunostaining for endothelial NOS (eNOS) was observed in lamina propria macrophages and colonic blood vessels, and eNOS protein levels were increased in the inflamed colon. These results show that there is no difference in UC-associated cancer development in iNOS+/+ and iNOS-/- mice, and suggest that in the absence of iNOS, other factors, such as eNOS, may play a role in nitrosative stress and UC-associated carcinogenesis in this model system.

Protective effect of orally administered carnosine on bleomycin-induced lung injury

Carnosine is an endogenously synthesized dipeptide composed of beta-alanine and L-histidine. It acts as a free radical scavenger and possesses antioxidant properties. Carnosine reduces proinflammatory and profibrotic cytokines such as transforming growth factor-beta (TGF-beta), IL-1, and TNF-alpha in different experimental settings. In the present study, we investigated the efficacy of carnosine on the animal model of bleomycin-induced lung injury. Mice were subjected to intratracheal administration of bleomycin and were assigned to receive carnosine daily by an oral bolus of 150 mg/kg. One week after fibrosis induction, bronchoalveolar lavage (BAL) cell counts and TGF-beta levels, lung histology, and immunohistochemical analyses for myeloperoxidase, TGF-beta, inducible nitric oxide synthase, nitrotyrosine, and poly(ADP-ribose) polymerase were performed. Finally, apoptosis was quantified by terminal deoxynucleotidyltransferase-mediated UTP end-labeling assay. After bleomycin administration, carnosine-treated mice exhibited a reduced degree of lung damage and inflammation compared with wild-type mice, as shown by the reduction of 1) body weight, 2) mortality rate, 3) lung infiltration by neutrophils (myeloperoxidase activity and BAL total and differential cell counts), 4) lung edema, 5) histological evidence of lung injury and collagen deposition, 6) lung myeloperoxidase, TGF-beta, inducible nitric oxide synthase, nitrotyrosine, and poly(ADP-ribose) polymerase immunostaining, 7) BAL TGF-beta levels, and 8) apoptosis. Our results indicate that orally administered carnosine is able to prevent bleomycin-induced lung injury likely through its direct antioxidant properties. Carnosine is already available for human use. It might prove useful as an add-on therapy for the treatment of fibrotic disorders of the lung where oxidative stress plays a role, such as for idiopathic pulmonary fibrosis, a disease that still represents a major challenge to medical treatment.

The receptor for advanced glycation end products and its ligands: a new inflammatory pathway in lung disease?

The binding of the receptor for advanced glycation end products (RAGE) with its ligands begins a sustained period of cellular activation and inflammatory signal amplification in different tissues and diseases. This binding could represent an as yet uninvestigated pathway of inflammatory reaction in the lung, where the presence of the receptor has been largely documented and advanced glycation end products (AGEs) are produced by nonenzymatic glycation and oxidation of proteins and lipids, driven by smoke and pollutants exposure or inflammatory stress. We immunohistochemically assessed the expression of RAGE and of its major proinflammatory ligands, N-epsilon-carboxy-methyl-lysine, S100B and S-100A12 in normal lung and in non-neoplastic lung disorders including smoke-related airway disease, granulomatous inflammation, postobstructive damage and usual interstitial pneumonia. In normal lung low expression of the receptor was observed in bronchiolar epithelia, type II pneumocytes, macrophages and some endothelia. S100A12 and S100B were expressed, respectively, in granulocytes and in dendritic cells. Carboxy-methyl-lysine was present in bronchiolar epithelia and macrophages. In all pathological conditions associated with inflammation and lung damage overexpression of both the receptor and of AGEs was observed in bronchiolar epithelia, type II alveolar pneumocytes, alveolar macrophages and endothelia. RAGE overexpression was more evident in epithelia associated with inflammatory cell aggregates. Fibroblasts in usual interstitial pneumonia expressed both the receptor and AGEs. The number of S100A12 and S100B immunoreactive inflammatory cells was variable. S100A12 was also expressed in mononuclear inflammatory cells and in activated epithelia. The activation of the inflammatory pathway controlled by the RAGE is not specific of a single lung disease, however, it may be relevant as a nonspecific pathway of sustained inflammation in lung tissue, and on this basis therapeutic approaches based on receptor blockage can be envisaged.

Extracellular superoxide dismutase has a highly specific localization in idiopathic pulmonary fibrosis/usual interstitial pneumonia

AIMS

Recent studies suggest the importance of oxidant stress in the progression of pulmonary fibrosis. The aim of this study was to investigate extracellular superoxide dismutase (ECSOD), the major antioxidant enzyme of the extracellular matrix of human lung, in biopsy-proven idiopathic pulmonary fibrosis (IPF) related to usual interstitial pneumonia (UIP).

METHODS AND RESULTS

Fibrotic areas and fibroblastic foci in UIP lungs were notable for absence of ECSOD by immunohistochemistry. Western blotting showed significantly lowered immunoreactivity of ECSOD in fibrotic compared with non-fibrotic areas of the diseased lung. The only cell type that showed intense ECSOD positivity in UIP was the interstitial mast cell. In order to investigate the mechanism for ECSOD depletion in fibrotic areas, alveolar epithelial cells were exposed to tumour necrosis factor-alpha and transforming growth factor (TGF)-beta1; TGF-beta suggested a trend towards decreased synthesis. Patients with UIP were also assessed to determine whether this disease is associated with a naturally occurring mutation in ECSOD (Arg213Gly) which leads to a loss of tissue binding of ECSOD. No significant differences could be found in the allele or genotype frequencies of this polymorphism between 63 UIP patients and 61 control subjects.

CONCLUSION

Overall, consistent with several other antioxidant enzymes, ECSOD is very low in fibrotic areas of UIP, which may further increase the oxidant burden in this disease.

Nitric oxide synthases are associated with bronchial dysplasia

Recent studies suggest that reactive oxygen (ROS) and nitrogen species (RNS) are highly associated with the pathogenesis of cigarette smoke related lung diseases but their role in the malignant conversion of bronchial epithelium is unclear. The immunohistochemical expression of inducible, endothelial and neuronal nitric oxide synthases (iNOS, eNOS and nNOS) and nitrotyrosine as a biomarker of oxidative/nitrosative stress was evaluated in 79 cases including 13 non-smokers, 20 smokers without chronic obstructive pulmonary disease (COPD), 22 with COPD and 24 with metaplasia-dysplasia-sequence of the bronchial epithelium. Normal lung of non-smokers was mainly negative for nitrotyrosine, while it was higher in the alveolar macrophages of cigarette smokers and COPD than in non-smokers (p=0.025, p<0.001), and in the alveolar epithelium of smokers and COPD than in non-smokers (p=0.049). There were no major differences in the nitrotyrosine immunoreactivity between the metaplastic/dysplastic lesions and bronchial epithelium of cigarette smokers. Inducible NOS and nNOS were mainly non-detectable or weak in the normal looking bronchial epithelium of smokers and COPD, whereas metaplasia and dysplasia showed positivity for iNOS (22/24) and nNOS (14/24) in the majority of cases. Strong immunoreactivity for iNOS and nNOS was also found more often in dysplastic than metaplastic (p=0.011 and p=0.049, respectively) specimens. Thus, smoking can cause protein nitration also in normal lung. Prominent iNOS and nNOS immunoreactivity in the metaplasia-dysplasia-lesions suggests a divergent role of NOSs in lung carcinogenesis.

In situ assessment of oxidant and nitrogenic stress in bleomycin pulmonary fibrosis

Reactive oxygen species (ROS) and nitric oxide (NO) have a role in the development of pulmonary fibrosis after bleomycin administration. The ROS production induces an antioxidant response, involving superoxide dismutases (SODs), catalase, and glutathione peroxidases. We compared in situ oxidative burden and antioxidant enzyme activity in bleomycin-injured rat lungs and normal controls. ROS expression and catalase, glucose-6-phosphate-dehydrogenase (G6PHD), and NOS/NADPH-diaphorase activity were investigated by using histochemical reactions. Nitric oxide synthase (e-NOS and i-NOS) and SOD (MnSOD, Cu/ZnSOD, ECSOD) expression was investigated immunohistochemically. After treatment ROS production was enhanced in both phagocytes and in type II alveolar epithelial cells. Mn, Cu/Zn, and ECSOD were overexpressed in parenchymal cells, whereas interstitium expressed ECSOD. Catalase and G6PHD activity was moderately increased in parenchymal and inflammatory cells. NOS/NADPH-d activity and i-NOS expression increased in alveolar and bronchiolar epithelia and in inflammatory cells. It can be suggested that the concomitant activation of antioxidant enzymes is not adequate to scavenge the oxidant burden induced by bleomycin lung damage. Inflammatory cells and also epithelial cells are responsible of ROS and NO production. This oxidative and nitrosative stress may be a substantial trigger in TGF-beta1 overexpression by activated type II pneumocytes, leading to fibrotic lesions.

Exhaled nitric oxide in sarcoidosis

BACKGROUND

Increased production of nitric oxide (NO) by the lower respiratory tract is viewed as a marker of airway inflammation in asthma and bronchiectasis. NO is a potentially important immune modulator, inhibiting the release of several key pro-inflammatory cytokines. As sarcoidosis is characterised by granulomatous airway inflammation, we hypothesised that exhaled NO levels might be raised in sarcoidosis and correlate with the morphological extent and functional severity of disease.

METHODS

Fifty two patients with sarcoidosis (29 men) of mean age 42 years underwent thin section computed tomography (CT), pulmonary function tests, and measurement of exhaled NO.

RESULTS

Exhaled NO levels (median 6.8 ppb, range 2.4-21.8) did not differ significantly from values in 44 control subjects, and were not related to the extent of individual CT abnormalities or the level of pulmonary function impairment.

CONCLUSION

Exhaled NO levels are not increased in pulmonary sarcoidosis.

Oxidative stress in pulmonary fibrosis: a possible role for redox modulatory therapy

Idiopathic ulmonary fibrosis (histopathology of usual interstitial pneumonia) is a progressive lung disease of unknown etiology. No treatment has been shown to improve the prognosis of the patients with this disease. Recent evidence, including the observations that the patients with idiopathic pulmonary fibrosis have higher levels of oxidant stress than control patients, and a recent multicenter European study examining the effect of the antioxidant N-acetylcysteine on the progression of idiopathic pulmonary fibrosis suggest that the cellular redox state may play a significant role in the progression of this disease. These complex mechanisms include activation of growth factors as well as regulation of matrix metalloproteinases and protease inhibitors. Potential future approaches for the therapy of interstitial pulmonary fibrosis may involve synthetic agents able to modulate cellular redox state. Investigation into therapeutic approaches to inhibit oxidant-mediated reactions in the initiation and progression of pulmonary fibrosis may provide hope for the future treatment of this disease.

Nitric oxide-induced persistent inhibition and nitrosylation of active site cysteine residues of mitochondrial cytochrome-c oxidase in lung endothelial cells

Persistent inhibition of cytochrome- c oxidase, a terminal enzyme of the mitochondrial electron transport chain, by excessive nitric oxide (NO) derived from inflammation, polluted air, and tobacco smoke contributes to enhanced oxidant production and programmed cell death or apoptosis of lung cells. We sought to determine whether the long-term exposure of pulmonary artery endothelial cells (PAEC) to pathophysiological concentrations of NO causes persistent inhibition of complex IV through redox modification of its key cysteine residues located in a putative NO-sensitive motif. Prolonged exposure of porcine PAEC to 1 mM 2,2′-(hydroxynitrosohydrazino)-bis-ethanamine (NOC-18; slow-releasing NO donor, equivalent to 1–5 μM NO) resulted in a gradual, persistent inhibition of complex IV concomitant with a reduction in ratios of mitochondrial GSH and GSSG. Overexpression of thioredoxin in mitochondria of PAEC attenuated NO-induced loss of complex IV activities, suggesting redox regulation of complex IV activity. Sequence analysis of complex IV subunits revealed a novel putative NO-sensitive motif in subunit II (S2). There are only two cysteine residues in porcine complex IV S2, located in the putative motif. Immunoprecipitation and Western blot analysis and “biotin switch” assay demonstrated that exposure of PAEC to 1 mM NOC-18 increased S-nitrosylation of complex IV S2 by 200%. Site-directed mutagenesis of these two cysteines of complex IV S2 attenuated NO-increased nitrosylation of complex IV S2. These results demonstrate for the first time that NO nitrosylates active site cysteines of complex IV, which is associated with persistent inhibition of complex IV. NO inhibition of complex IV via nitrosylation of NO-sensitive cysteine residues can be a novel upstream event in NO-complex IV signaling for NO toxicity in lung endothelial cells.

Pathogenesis of hypersensitivity pneumonitis

PURPOSE OF REVIEW

Hypersensitivity pneumonitis is a group of immunologically mediated diseases caused by an abnormal response to a wide variety of inhaled antigens. Its pathogenesis is complex and involves many immunological concepts. This review discusses recent advances in our understanding of the pathogenesis of hypersensitivity pneumonitis.

RECENT FINDINGS

Over the last 3 years, several studies on the pathogenesis of hypersensitivity pneumonitis have been published. New antigens have been identified. We now have a better understanding of the role of inflammatory cells and mediators, and promoting and protective factors have been suggested.

SUMMARY

Most of the mechanisms involved in the pathogenesis of hypersensitivity pneumonitis remain incompletely understood. Current and future findings will not only help our understanding of the disease and its prevention, but also improve its treatment.

Superoxide dismutases in the lung and human lung diseases

The lungs are directly exposed to higher oxygen concentrations than most other tissues. Increased oxidative stress is a significant part of the pathogenesis of obstructive lung diseases such as asthma and chronic obstructive pulmonary disease, parenchymal lung diseases (e.g., idiopathic pulmonary fibrosis and lung granulomatous diseases), and lung malignancies. Lung tissue is protected against these oxidants by a variety of antioxidant mechanisms among which the superoxide dismutases (SODs) are the only ones converting superoxide radicals to hydrogen peroxide. There are three SODs: cytosolic copper-zinc, mitochondrial manganese, and extracellular SODs. These enzymes have specific distributions and functions. Their importance in protecting lung tissue has been confirmed in transgenic and knockout animal studies. Relatively few studies have been conducted on these enzymes in the normal human lung or in human lung diseases. Most human studies suggest that there is induction of manganese SOD and, possibly, extracellular SOD during inflammatory, but not fibrotic, phases of parenchymal lung diseases and that both copper-zinc SOD and manganese SOD may be downregulated in asthmatic airways. Many previous antioxidant therapies have been disappointing, but newly characterized SOD mimetics are being shown to protect against oxidant-related lung disorders in animal models.

Applied clinical immunology in sarcoidosis

Staging of sarcoidosis needs a synthesis of clinical features, histology, radiology, biochemical changes, and immunologic aberrations to distinguish this disease from nonspecific sarcoid-tissue reactions. The main aim of this report is to offer readers an overview on immunologic markers that have been evaluated in the last years with the ultimate goal of relating their determination to the management of the disease. The first part is devoted to immunologic markers that have been proposed to define the activity of the T-cell component of the sarcoid inflammatory process. In the second part of the paper, we will provide a descriptive definition of immunologic markers of activity of sarcoid macrophages relating them to the clinical course of sarcoidosis.